Outside the headlines, something else has been happening since Sterling was shot: The Baton Rouge Police Department has substantially reduced enforcement of narcotics offenses. That may sound like a small change, but narcotics enforcement can be an important glimpse into how often officers are going out of their way to engage in police work. Police officers do both reactive work (responding to 911 calls, for example) and proactive work (such as traffic stops that lead to drug arrests). In a moment of heightened tension between the police and a city’s residents, the trends in proactive policing can tell us whether officers are engaging with residents more or less often than they once did.

And a reduction in proactive policing could have a broader effect on Baton Rouge as a whole. Higher levels of violence have followed a reduction in narcotics enforcement in some cities whose police departments have been involved in high-profile deaths or the protests that followed. Will the same thing occur in Baton Rouge?

Baton Rouge’s open data portal provides information on more than 27,000 narcotics offenses1 from January 2011 to the present, and a review of those showed a clear change after Sterling was shot. The Baton Rouge Police Department averaged 94 narcotics offenses per week2 from the start of 2011 through July 4, 20163 — the day before Sterling was killed. But in the seven days after Sterling was killed (July 6-12), there were only 22 narcotics offenses — 77 percent fewer than the average.4 The only other large dip in the 18 months preceding the most recent one came between Christmas of 2015 and New Year’s Day.

That seven-day total of 22 narcotics offenses was, at the time, the smallest of any seven-day period since the beginning of 2011, the earliest data available via the city’s open-data portal.

The specific reason for the apparent drop in proactive policing in Baton Rouge is unclear. The police department did not respond to multiple requests for comment, and the office of Baton Rouge Mayor Kip Holden declined to comment for this story.

The drop may be the result of the short-term response of a police department whose capabilities were stretched thin by protests held in response to the Sterling shooting and was still reeling from the Dallas attack on police officers. The Baton Rouge Advocate reported that officers were required to work 12-hour shifts with no days off in the immediate aftermath of the Sterling shooting, and officers began patrolling in pairs on July 12, several days after the attack on police officers in Dallas.

Ronal Serpas, who previously served as police chief in New Orleans and Nashville, said in an interview that a short-term decline in proactive policing may be natural when a department responds to lengthy protests. (I worked as a crime analyst in New Orleans under Serpas.) “An immediate realignment of resources to protest policing generally requires that you reassign all of your proactive units — i.e., narcotics units, detectives units and other staff headquarters units,” Serpas said.

The change could also reflect a longer-term change in policing. In May, when asked about the possibility that police departments might be pulling back on enforcement efforts, FBI Director James Comey referred to the “viral video effect” — the idea that officers fear a backlash if they were to be involved in a hostile encounter that was caught on camera. “There’s a perception that police are less likely to do the marginal additional policing that suppresses crime — the getting out of your car at 2 in the morning and saying to a group of guys, ‘What are you doing here?’” Comey said.

In three other cities — Baltimore, Chicago and St. Louis — I found a similar drop in proactive policing, as measured by the change in drug enforcement,5 after demonstrations against high-profile deaths of black men involving police officers. Roughly six months after Michael Brown was killed by a police officer in the St. Louis suburb of Ferguson, drug enforcement in St. Louis had mostly recovered to the levels before the shooting. (Both Brown’s death and the protests that followed occurred outside the city of St. Louis. But St. Louis police participated directly in the response to the demonstrations in Ferguson, and the protests brought additional media and activist scrutiny to police behavior in St. Louis itself.) In Chicago and Baltimore, narcotics enforcement is still occurring far less frequently than before the November 2015 release of the video of the shooting of Laquan McDonald and the April 2015 death of Freddie Gray, respectively.6

After drug enforcement in those three cities fell, the number of murders rose significantly. For each city, I looked at the number of murders in the four months before the month of the incident and the four months after, comparing each stretch of months to the number of murders in those same months the previous year.7 Here’s how that worked in practice, using Baltimore as an example: Gray died in April 2015. In the four months before April (December 2014 through March 2015), 51 people were murdered in Baltimore, fewer than were killed in the same four months the previous year. In the four months that followed April, though, murders increased to 151 compared with 91 in the same period the previous year. You can see the changes for the three cities on the chart adjacent to this paragraph.

(If you’re interested in exploring those trends more, an article in FiveThirtyEight earlier this year showed that the drop in proactive policing was closely correlated with gun violence rising in Chicago, and another showed a similar effect occurring in Baltimore last year.)

It’s too early to tell what effect (if any) Baton Rouge’s apparent drop in proactive policing will have on long-term violence trends in the city. And even when enough time has passed, it will be difficult to assess the trends. Baton Rouge has far fewer annual murders than Chicago, Baltimore and St. Louis have, so knowing when a short-term spike or drop is a real change, as opposed to a temporary blip, won’t be easy.

Footnotes

Police departments vary in how they publicly report data on crimes and arrests. In its data portal, Baton Rouge includes detailed information on “offenses,” a term that is synonymous with “crimes.” Each offense is assigned a category, such as “homicide” or narcotics, as well as a date, location and description.

Sixty percent of all offenses were possession of marijuana or drug paraphernalia. The other 40 percent were drug distribution (23 percent), possession of drugs other than marijuana (15 percent), and other assorted drug offenses (under 2 percent).

The numbers can vary widely, but there were at least 60 offenses in 97 percent of seven-day periods since the start of 2011.

There seems to be a delay between when an offense occurs and when it appears in the database. These delays appear to be mostly resolved after about a week. Because of the delay, the chart of narcotics offenses in Baton Rouge does not include data beyond July 16. The data was downloaded on July 25th.

The data made available to the public by Baltimore, Chicago and St. Louis is slightly different from what Baton Rouge reports, but each of the three cities provides something similar to Baton Rouge’s “offenses” that can be used as a proxy for narcotics enforcement. Chicago reports “narcotics incidents,” while St. Louis reports “drug incidents.” A single criminal incident can contain multiple offenses — for example, an incident could be a drug bust for both a possession of marijuana offense and a possession of cocaine offense. Baltimore provides data on narcotics arrests, rather than offenses or incidents, and here, I’ve used “controlled dangerous substance” arrests to represent drug enforcement there.

McDonald was fatally shot by a Chicago police officer in October 2014; widespread protests over the shooting did not begin until November 2015, when videos of the incident were released. Gray suffered a spinal cord injury while in the custody of Baltimore police on April 12, 2015, and died seven days later.

I compared the change in number of murders in the months before and after the month of the incident to avoid seasonal effects. If there are typically more murders than average during the time of year that immediately preceded an incident, that should be true in the same period a year before. I left out the month the incident occurred to prevent the data from being influenced by how deep into a month the incident took place.

Jeff Asher is based in New Orleans and used to work for the city as a crime analyst. He currently does crime analysis for the Jefferson Parish Sheriff’s Office and runs the NOLA Crime News data analysis blog. @Crimealytics